Nannofossil absolute abundances of sediment core GeoB2204-2

The calcareous nannofossil assemblages from sediment core GeoB2204-2 from the western equatorial region off Brazil were examined to document oceanographic changes in surface waters during the last 155 ka. Coccolith counts (N) were made manually using a Zeiss DSM 940A scanning electron microscope at 3,000x or 5,000x magnification. The recorded fluctuations in the abundance and composition of coccolithophore communities reflect changes in surface water masses. The community is dominated by species from the deeper photic zone, such as Florisphaera profunda and Gladiolithus flabellatus, indicating predominantly oligotrophic conditions during glacial periods. During interglacial periods, higher abundances and larger proportions of species with an affinity for nutrient-rich surface waters indicate the highest abundances.